In wall gutter downspout causing mold on drywall.
 

Hi all,

Here is my situation:

A unit in my townhouse complex (I'm the strata president) has a vertical line of mold on the drywall of the exterior garage wall. The mold is inline with a gutter downspout that is embedded in the wall. Upon opening the wall, it was easy to see condensation forming on the downpipe which would cause the mold. This is the only unit that I know of that has had this issue so I wonder if this particular downpipe is not properly centered on the footer of the wall and is close enough to the drywall such that condensation on the pipe actually touches the drywall.

We have had two contractors quote the repair; one ridiculous ($17k) and another much better ($1800) but I think even that one may still be overkill. I'm curious to know what you all think.

The lower quote is for the following items:

1. Remove all drywall along outside wall of garage showing signs of moisture and dispose of damaged material.
2. Seal any holes or cracks in exterior finish from inside the garage to seal out moisture
3. Insulate exterior wall with R14 Roxul insulation, and then apply a Vapour barrier
4. Re-drywall, tape, mud and sand and prep for painting
5. Supply and install two coats of a premium grade Devoe eggshell finish paint to all walls and ceiling in garage after all drywall is finished.
6. Re-install any racks and wall mounted items that are currently on walls

My concerns are as follows:

Removing the entire wall's drywall seems excessive when the area affected is less than the area between two studs. It seems like that is being proposed in order to insulate that wall which brings my next question. Why would they insulate and add vapour barrier to an exterior wall that has an unheated garage on the inside? To me it seems that only the downpipe needs insulation and/or a vapour barrier behind the drywall between the studs on either side of the downpipe in order to prevent condensation from ocurring in that section of the wall. The rest of the wall should have no issues as there is low enough moisture and sufficient air flow.

Is my reasoning correct/incorrect? If the quoted work makes sense then I am more than happy to get the work done but, if not, I would like to go back to them and ask for a new quote that involves just replacing a 4'x8' section of the drywall and insulation(bubble-wrap type?)/vapour barrier installation only between the joists containing the downpipe.

Comments? Thx,

Chris P.

His proposal is not to"remove the entire walls drywall"--Only the parts showing signs of moisture.

How did the other contractor proposed to keep the humidity from reaching the cold pipe?

Mike, thanks for your comment. It's amazing how many times I can read something and never read it correctly. That eliminates one of my concerns.

Here is the work quoted from the first contractor for ~$17k:

Temp. storage for items in garage
Remove all drywall in garage
Spray wood with anit-fungal spray solution
Investigation of leak
Repair of leak
Wrap pipe in compound pipe insulation
Replace drywall with humid tech drywall - mold resistant material
3 coats of drywall compound on textured ceilings
Reinstall garage door motor
Primer and 2 coasts of paint
$750 Allowance for roof repair

Would compound pipe insulation be a better solution than fiberglass + vapour barrier?

That's hard, when you get two quotes that are that far apart in price! Either one is ripping you off, or one is not fixing something that should be...that's a hard call, especially without seeing the situation first hand.

That $17,000 job is serious over kill---The less expensive one might be missing the cause of the problem and only addressing the symptoms---

Does your association deal with a roofing contractor that you respect?

Experienced roofers are amazing at finding water infiltration problems----I suspect that the diagnosis of 'condensation' might not be accurate.

Offer money or a nice lunch to your roofer to find the cause of that mold---then you will be in a good position to make a decision on the wisest fix for the problem.

Mike

I'd like to have a comment or two from a roofer--am I off base suggesting your trade to find the cause of this?

I agree.

One contractor told you “Seal any holes or cracks in exterior finish from inside the garage to seal out moisture”. :eek: That statement alone tells me this guy’s dangerous.

I’d stay away from both of those contractors. How can you give a price on a repair when you don’t even know the cause.

I find it hard to believe this is condensation isolated to just one unit and assuming this was never a problem before.

Is this a flat roof with parapet walls? What kind of siding? Pictures inside and out always help here.

I’m thinking you may need two contractors, one to diagnose and repair the leak (probably a roofer) and another to repair the damage once the problem is solved.

I wouldn’t let anyone cover up anything until the your positive the problem has been solved.

We cut away a section of the moldy drywall to expose the downpipe which is why I'm quite confident that condensation on the pipe is part or all of the issue. The in-wall downpipe is covered with condensation on rainy days (this is Vancouver BC area, think of Seattle weather but more rain) and the mold line is in perfect alignment with the downpipe.

The siding is just wood clapboard and that makes me think it would almost be impossible to seal out all moisture from getting into the wall.

So far the owners of this unit are the only ones to have notified council of this issue. There are only a few units in our complex that have a gutter downpipe in the wall, most have the downpipe attached to the exterior.

Condensation, leak or both really doesn’t matter the downspout doesn’t belong in the wall and should be moved to the outside where it belongs.

Since mold is a health issue and your renting your best coarse of action is stay on top of the owner until this is resolved.

Has anyone called a roofer yet?

Has it occurred to you that the drain may be plugged up and holding cold water?

Why would it be cold if there is not water in it?

This isn't a rental unit, it is a townhouse complex where each unit is owned by the individual but maintenance (of structures and landscaping) is guided by a strata council using funds acquired through monthly strata payments by the owners.

Mike, we do get very heavy rainfall here on a fairly regular basis that would be able to keep that downpipe cold for an extended period of time (days, not hours) but I think your suggestion is worth looking into.

No roofer has been called as:
- I think there would have to be one hell of a coincidence for a mold line that is in perfect alignment with downpipe to be due to something else other than the downpipe.
- After cutting away the drywall to access the downpipe, we have observed condensation forming on the entire length of the downpipe but the owner has not reported any other water ingress in that area of the wall.

I agree that the design is inherently dumb but relocating the downpipe is not feasible.

If you're sure that there is no leak----call an insulation contractor that will install spray foam--

That will surround the pipe and completely fill the cavity----then use Dense Shield (a completely water proof fiberglass covered drywall) in that area.

Over kill--maybe---done forever? Yes.----Mike---